machines = 1:7;
groupcount = 3;
minmachinepergroup = 2;
minmachines = minmachinepergroup * groupcount;
assert(numel(machines) >= minmachines, 'Not enough to fill the minimum in each goup');
rmachines = machines(randperm(numel(machines))); %randomise the machines
groupdest = [repmat(1:groupcount, 1, minmachinepergroup), randi(groupcount, 1, numel(machines) - minmachines)]; %distribute first the minimum per group, then randomise
groups = accumarray(groupdest(:), rmachines, [], @(v) {v}); %distribute the machines into the groups
